This research plan proposes two projects designed to expand the genetic potential of the oncogenic DNA virus, Simian Virus 40, and its host cells. The goal of the first is to define SV40-host genome interactions. SV40-resistant permissive cell lines will be isolated from among the survivors of an SV40 lytic infection. The blocks to infection in these lines will be pinpointed by physiological and biochemical characterization. Whether the resistant state is induced by SV40 infection will be determined by standard fluctuation analysis. If resistance is induced by infection, integrated SV40 DNA will be assayed by analysis of DNA renaturation kinetics. The goal of the second project is to develop methods for genetic analysis of SV40. Two methods that use bacterial restriction enzymes will be tested: 1) a novel recombinational method that utilizes in vitro-constructed mixed dimers and 2) a technique that relies on salvage of markers from fragments of wild type DNA annealed to single stranded, circular, mutant DNA. These two techniques should permit fine-structure genetic mapping and precise orientation of genes relative to the SV40 physical map.